Recurrent Hyponatremia as the Presenting Feature of Empty Sella

Hyponatremia, an abnormal laboratory symptom rather than a specific disease needs the detailed search for the underlying causes. A 71-year-old female was found to have recurrent hyponatremia associated with weakness, lightheadedness and fatigue twice in the past 3 months. She had no history of psychiatric drugs administration, and previous pituitary surgery or postpartum hemorrhage. Her hyponatremia (108 mmol/L) met the laboratory diagnostic criteria of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and was refractory to watery restriction, salt and fluid substitution alone. Endocrine studies were relatively normal including serum cortisol and thyroxine. However, provocative test with 250•g of co-syntropin is partial response to this patient. Magnetic Resonance Imaging of brain clearly demonstrated an empty sella with cerebrospinal fluid filling in the sella turcica and flattened pituitary gland against sellar floor. Secondary adrenal insufficiency associated with empty sella was highly contributory to hyponatremia. Hyponatremia completely resolved after prednisolone supplementation. This case highlights the fact that recurrent hyponatremia mimicking SIADH may be the presenting feature of empty sella.

並列關鍵字

empty sella ； hyponatremia ； syndrome of inappropriate secretion of antidiuretic hormone

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